In vitro synthesis of oviductal proteins associated with estrus and 17 beta-estradiol-treated ovariectomized ewes.

The objectives of this study were: 1) to identify and characterize ewe oviductal secretory proteins (OSP) de novo synthesized during the estrous cycle; 2) to examine the effect of estrogen (E) and progesterone (P) on synthesis of OSP; and 3) to determine synthesis of OSP by ampulla (A) and isthmus (I). Oviducts were collected from cyclic ewes on days 1, 8, and 16 and ovariectomized (OVX) ewes after treatment with corn oil (CO), E, P, and E + P. Tissue was incubated in the presence of 3H-leucine or 3H-glucosamine. Rates of 3H-leucine incorporation into nondialyzable macromolecules by explants was greater (P less than 0.05) on day 1 than days 8 and 16, greater (P = 0.01) in OVX E-treated ewes, greater in A than I regardless of treatment and greater (P less than 0.05) in A than I with E. Culture medium was analyzed by one- and two-dimensional polyacrylamide gel electrophoresis and fluorography. Two major basic proteins (Mr 90-92,000) and three minor proteins were only present on day 1 of estrus. E treatment demonstrated these same proteins which were not found with CO or P treatment. Two-dimensional analysis of medium from A and I cultured separately indicated that A synthesized the two major basic and three minor E-dependent proteins. Of three protein complexes present regardless of treatment or cycle day, two were dominant in the A and one was dominant in the I suggesting a synthetic gradient. Tunicamycin did not inhibit incorporation of 3H-glucosamine into E-dependent proteins. Gel filtration revealed a high Mr fraction (2 x 10(6] 2.5-fold greater on day 1 than day 8 and 2.2-fold greater with E than CO treatment. This study clearly demonstrates: 1) that the oviduct from estrus and E-treated ewes synthesizes two major basic and three minor glycoproteins not detectable on other cycle days or with OVX or P treatment; 2) the E-dependent glycoproteins are synthesized by the A; and 3) a high Mr fraction is induced or amplified by E.